This invention relates to thoracic drainage apparatus of the type including a collection chamber and a suction source, and more particularly to a control module for regulating the removal of gases from the collection chamber to the suction source.
Various types of thoracic drainage devices have been developed for draining fluids from the pleural cavity of a human being into a collection chamber maintained at a negative pressure. The principal function of a thoracic drainage device is to evacuate gases and liquids from the pleural cavity in order to restore the normally negative intrapleural pressure and permit proper expansion of the patient's lungs. To accomplish this, the device must include a one-way seal which permits gases to flow out of the pleural cavity and into the drainage device but which prevents the return of any gases from the drainage device toward the pleural cavity. Two types of one-way seals have been used, an underwater seal and a one-way mechanical seal (e.g., umbrella valve).
In addition to a one-way seal, thoracic drainage devices include other means for regulating the flow of gases through the device. See, for example, U.S. Pat. Nos. 4,544,370 to Elliott et al., 4,468,226 to Kurtz et al., and 4,465,483 to Weilbacher. A suction control regulator is provided to control the amount of suction applied by the suction source to the collection chamber. An indicator means is provided to show the level of applied suction. A positive pressure relief means is provided to relieve any positive pressure buildup in the device when the patient coughs or in the event of a system malfunction. A negative pressure relief means is provided to relieve any excess negative pressure caused, for example, by a sharp inspiration or by stripping the patient tube leading from the pleural cavity to the collection chamber. A liquid-filled U-tube or air leak indicator is provided through which the gases exiting the pleural cavity can be observed as they bubble through the liquid.
Thoracic drainage devices are widely used in ambulatory care and thus such devices should be compact, easy to handle, nonbreakable, and their operation should not be affected if inclined or tilted. For transportation on a bedrail, the device should be of a reduced height.
It would be desirable to provide a thoracic drainage device in modular form wherein the modular components can be combined to produce a number of different size and type drainage devices. Previous attempts to produce a modular thoracic drainage device are shown in U.S. Pat. Nos. 3,847,152 to Schachet, 4,439,190 to Protzmann et al., and 4,465,483 to Weilbacher; see also the modular urine discharge measuring system shown in U.S. Pat. No. 4,448,207 to Parrish. In these known modular thoracic drainage devices, the various system components, such as the collection chamber, the one-way seal means, the pressure regulating means, etc., are formed as separate modular components which can be connected together to form a modular unit. None of these prior art devices is significantly more compact or adaptable and each has many more connections between components and thus an increased risk of air leakage.